1. The Field of the Invention
This application relates generally to drill bits and methods of making and using such drill bits. In particular, this application relates to impregnated drill bits with aggressive face-profiles, as well as to methods for making and using such drill bits.
2. The Relevant Technology
While many different drilling processes are used for a variety of purposes, in most drilling processes a drill head applies axial forces (feed pressure) and rotational forces to drive a drill bit into a formation. More specifically, a bit is often attached to a drill string, which is a series of connected drill rods coupled to the drill head. The drill rods are assembled section by section as the drill head moves and drives the drill string deeper into the desired sub-surface formation. One type of drilling process, rotary drilling, involves positioning a rotary cutting bit at the end of the drill string. The rotary cutting bit often includes cutters that are distributed across the face of the rotary cutting bit.
Bits can be impregnated with diamonds so that they can be used to cut hard formations and/or to increase the durability of the bit. The part of the bit that performs the cutting action, sometimes referred to as a face, is generally formed of a matrix that contains a powdered metal or a hard particulate material, such as tungsten carbide. This material is sometimes infiltrated with a binder, such as a copper alloy. The matrix and binder associated with the face are mixed with diamond crystals or some other form of abrasive cutting media. As the tool grinds and cuts the desired materials, the matrix and binder erode and expose new layers of the diamond crystal (or other cutting media) so that a sharp surface is always available for the cutting process.
In order for a new bit to drill a formation, some portion of the matrix and binder often must be eroded away in order to expose a sufficient amount of the diamond to allow the diamond to cut the formation. Accordingly, often there is a break-in period for a bit after the bit is placed in rotating contact with a formation as the matrix wears to expose a sufficient amount of the diamonds for effective cutting. Such a process can increase the time associated with the corresponding drilling operations, and hence costs. This delay can be exacerbated if the bit is used in relatively soft formations as it may require a relatively long time to expose sufficient diamonds for effective cutting.
One approach to expose sufficient diamonds rapidly is to prepare the surface of the bit, such as by performing an initial grinding operation. In such an operation, the bit can efficiently cut as it rotates shortly after the bit is placed in contact with the formation. However, such a process still introduces additional time to the entire drilling operation, as well as the complexity associated with an additional step. Alternatively, this grinding process can be performed by the manufacturer of the bit, adding additional process time and cost.